Steam turbine electric generators, which are used in electric power-generating stations, are genrally of a substantial size. Ordinarily, the rotors of a turbine and a generator are mounted on a single shaft. The unit may weigh as much as 150 tons, and may be 35 feet long. When the steam turbine electric generators are in operation, they generally operate continuously, so that the shaft is constantly rotating. As is typical with any rotating mechanical device, it wears; and it is necessary to make repairs on the parts.
The size of the units ordinarily require that whatever repairs are to be made must be made at the power-generating station, rather than ship the units to a maintenance shop. One of the maintenance operations which must be performed on the shaft during an overhaul of the equipment is that the shaft must be turned, that is, the shaft must be shaved to make the shaft even. Accordingly, it is necessary to have a large turning device for supporting the shaft and turning it. One such device is disclosed in U.S. Pat. No. 4,034,631.
Although the turbine shaft weighs a substantial amount, it is necessary to turn the turbine shaft accurately and evenly. To this end, it is necessary to support the turbine shaft securely in a given attitude. This support of the turbine shaft is most important, so that machining of the shaft will be done with a high degree of precision.